Gefitinib, as an EGFR-TKI inhibitor, is contraindicated in patients with specific genotypes, pregnancy, and organ dysfunction, while also paying attention to drug interactions and dietary restrictions. The following provides a detailed explanation from three aspects: taboo populations, taboo foods, and medication restrictions.

1. Taboo population

(1) Genetic testing negative: EGFR mutation negative non-small cell lung cancer patients are contraindicated (objective response rate<10%).

(2) Pregnancy period: Animal studies have shown embryotoxicity, and pregnant women should use reliable contraceptive measures until 2 weeks after discontinuing medication.

(3) Severe liver injury: Not recommended for Child Pugh C patients (blood drug concentration can increase by 50%).

2. Forbidden foods

(1) Grapefruit products: Inhibiting CYP3A4 metabolism increases blood drug concentration by 2.5 times.

(2) High fat diet: Taking it with a standard meal can reduce AUC by 47%, and it should be taken on an empty stomach or 2 hours after a meal.

(3) St. John's wort: induces CYP3A4 to reduce drug exposure by 65%.

3. Medication restrictions

(1) Interstitial lung disease: It is contraindicated for patients with a medical history, and monitoring for newly developed respiratory distress is necessary during treatment.

(2) Liver function monitoring: ALT should be tested before treatment and monthly. If the ULN is greater than 5 times, the medication should be permanently discontinued.

(3) Ophthalmic examination: If symptoms of keratitis appear, medication should be immediately suspended.